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Date:   Thu, 22 Aug 2019 21:09:26 +0200
From:   Jacopo Mondi <jacopo@jmondi.org>
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     Jacopo Mondi <jacopo+renesas@jmondi.org>,
        kieran.bingham+renesas@ideasonboard.com, airlied@linux.ie,
        daniel@ffwll.ch, koji.matsuoka.xm@renesas.com, muroya@ksk.co.jp,
        VenkataRajesh.Kalakodima@in.bosch.com,
        Harsha.ManjulaMallikarjun@in.bosch.com,
        linux-renesas-soc@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 16/19] drm: rcar-du: kms: Collect CMM instances
Message-ID: <20190822190926.t2dm7nbaagnxgvns@uno.localdomain>
References: <20190706140746.29132-1-jacopo+renesas@jmondi.org>
 <20190706140746.29132-17-jacopo+renesas@jmondi.org>
 <20190820175457.GJ10820@pendragon.ideasonboard.com>
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Hi Laurent,

On Tue, Aug 20, 2019 at 08:54:57PM +0300, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Sat, Jul 06, 2019 at 04:07:43PM +0200, Jacopo Mondi wrote:
> > Implement device tree parsing to collect the available CMM instances
> > described by the 'cmms' property. Associate CMMs with CRTCs and store a
> > mask of active CMMs in the DU group for later enablement.
> >
> > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> > ---
> >  drivers/gpu/drm/rcar-du/rcar_du_crtc.c  |  6 +++
> >  drivers/gpu/drm/rcar-du/rcar_du_crtc.h  |  2 +
> >  drivers/gpu/drm/rcar-du/rcar_du_drv.h   |  3 ++
> >  drivers/gpu/drm/rcar-du/rcar_du_group.h |  2 +
> >  drivers/gpu/drm/rcar-du/rcar_du_kms.c   | 50 +++++++++++++++++++++++++
> >  5 files changed, 63 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> > index 2da46e3dc4ae..23f1d6cc1719 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.c
> > @@ -1194,6 +1194,12 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
> >  	if (ret < 0)
> >  		return ret;
> >
> > +	/* CMM might be disabled for this CRTC. */
> > +	if (rcdu->cmms[swindex]) {
> > +		rcrtc->cmm = rcdu->cmms[swindex];
> > +		rgrp->cmms_mask |= BIT(hwindex % 2);
> > +	}
> > +
> >  	drm_crtc_helper_add(crtc, &crtc_helper_funcs);
> >
> >  	/* Start with vertical blanking interrupt reporting disabled. */
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> > index 3b7fc668996f..5f2940c42225 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_crtc.h
> > @@ -39,6 +39,7 @@ struct rcar_du_vsp;
> >   * @vblank_wait: wait queue used to signal vertical blanking
> >   * @vblank_count: number of vertical blanking interrupts to wait for
> >   * @group: CRTC group this CRTC belongs to
> > + * @cmm: CMM associated with this CRTC
> >   * @vsp: VSP feeding video to this CRTC
> >   * @vsp_pipe: index of the VSP pipeline feeding video to this CRTC
> >   * @writeback: the writeback connector
> > @@ -64,6 +65,7 @@ struct rcar_du_crtc {
> >  	unsigned int vblank_count;
> >
> >  	struct rcar_du_group *group;
> > +	struct platform_device *cmm;
> >  	struct rcar_du_vsp *vsp;
> >  	unsigned int vsp_pipe;
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_drv.h b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> > index a00dccc447aa..300ec60ba31b 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_drv.h
> > @@ -13,6 +13,7 @@
> >  #include <linux/kernel.h>
> >  #include <linux/wait.h>
> >
> > +#include "rcar_cmm.h"
> >  #include "rcar_du_crtc.h"
> >  #include "rcar_du_group.h"
> >  #include "rcar_du_vsp.h"
> > @@ -70,6 +71,7 @@ struct rcar_du_device_info {
> >
> >  #define RCAR_DU_MAX_CRTCS		4
> >  #define RCAR_DU_MAX_GROUPS		DIV_ROUND_UP(RCAR_DU_MAX_CRTCS, 2)
> > +#define RCAR_DU_MAX_CMMS		4
> >  #define RCAR_DU_MAX_VSPS		4
> >
> >  struct rcar_du_device {
> > @@ -86,6 +88,7 @@ struct rcar_du_device {
> >  	struct rcar_du_encoder *encoders[RCAR_DU_OUTPUT_MAX];
> >
> >  	struct rcar_du_group groups[RCAR_DU_MAX_GROUPS];
> > +	struct platform_device *cmms[RCAR_DU_MAX_CMMS];
> >  	struct rcar_du_vsp vsps[RCAR_DU_MAX_VSPS];
> >
> >  	struct {
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_group.h b/drivers/gpu/drm/rcar-du/rcar_du_group.h
> > index 87950c1f6a52..b0c1466593a3 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_group.h
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_group.h
> > @@ -22,6 +22,7 @@ struct rcar_du_device;
> >   * @mmio_offset: registers offset in the device memory map
> >   * @index: group index
> >   * @channels_mask: bitmask of populated DU channels in this group
> > + * @cmms_mask: bitmask of enabled CMMs in this group
>
> enabled or available ?
>

I considered having a 'cmm' entry in DT as enabling it, but it is
actually just available.

> >   * @num_crtcs: number of CRTCs in this group (1 or 2)
> >   * @use_count: number of users of the group (rcar_du_group_(get|put))
> >   * @used_crtcs: number of CRTCs currently in use
> > @@ -37,6 +38,7 @@ struct rcar_du_group {
> >  	unsigned int index;
> >
> >  	unsigned int channels_mask;
> > +	unsigned int cmms_mask;
> >  	unsigned int num_crtcs;
> >  	unsigned int use_count;
> >  	unsigned int used_crtcs;
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> > index f8f7fff34dff..b79cda2f5531 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> > @@ -18,6 +18,7 @@
> >  #include <drm/drm_vblank.h>
> >
> >  #include <linux/of_graph.h>
> > +#include <linux/of_platform.h>
> >  #include <linux/wait.h>
> >
> >  #include "rcar_du_crtc.h"
> > @@ -534,6 +535,51 @@ static int rcar_du_vsps_init(struct rcar_du_device *rcdu)
> >  	return ret;
> >  }
> >
> > +static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
> > +{
> > +	const struct device_node *np = rcdu->dev->of_node;
> > +	unsigned int i;
> > +	int cells;
> > +
> > +	cells = of_property_count_u32_elems(np, "cmms");
> > +	if (cells == -EINVAL)
> > +		return 0;
> > +
> > +	if (cells > RCAR_DU_MAX_CMMS || cells > rcdu->num_crtcs) {
>
> Should this be
>
> 	if (cells != rcdu->num_crtcs)
>
> or do we want to support cases where not all DU channels have a CMM in
> DT ?
>

That was my idea yes, but I'm not sure it makes sense, as ideally CMM
should be specified in DT for all SoC that provides it.

> > +		dev_err(rcdu->dev, "Invalid 'cmms' property format\n");
>
> How about "Invalid number of entries in 'cmms' property" ?
>

Ok

> > +		return -EINVAL;
> > +	}
> > +
> > +	for (i = 0; i < cells; ++i) {
> > +		struct platform_device *pdev;
> > +		struct device_node *cmm;
> > +
> > +		cmm = of_parse_phandle(np, "cmms", i);
> > +		if (IS_ERR(cmm)) {
> > +			dev_err(rcdu->dev, "Failed to parse 'cmms' property\n");
> > +			return PTR_ERR(cmm);
> > +		}
> > +
> > +		pdev = of_find_device_by_node(cmm);
> > +		if (IS_ERR(pdev)) {
> > +			dev_err(rcdu->dev, "No device found for cmms[%u]\n", i);
>
> s/cmms[%u]/CMM%u/ ?
>
> > +			of_node_put(cmm);
> > +			return PTR_ERR(pdev);
> > +		}
> > +
> > +		if (!of_device_is_available(cmm)) {
>
> Should this come before the pdev check, as there will be no pdev in that
> case ?
>

No pdev if the device is not enabled in DT ? Anyway, yes, I could move
it up and save retrieving pdev in case the device is not available.

> > +			/* It's fine to have a phandle to a non-enabled CMM. */
> > +			of_node_put(cmm);
> > +			continue;
> > +		}
> > +
> > +		of_node_put(cmm);
> > +		rcdu->cmms[i] = pdev;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  int rcar_du_modeset_init(struct rcar_du_device *rcdu)
> >  {
> >  	static const unsigned int mmio_offsets[] = {
> > @@ -624,6 +670,10 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
> >  			return ret;
> >  	}
> >
> > +	/* Initialize the Color Management Modules. */
> > +	if (rcar_du_cmm_init(rcdu))
> > +		return ret;
>
> 	ret = rcar_du_cmm_init(rcdu);
> 	if (ret < 0)
> 		return ret;
>

Ups, this was probably returning void in some earlier version and I
failed to assign it properly, thanks for spotting this!

Thanks
   j

> > +
> >  	/* Create the CRTCs. */
> >  	for (swindex = 0, hwindex = 0; swindex < rcdu->num_crtcs; ++hwindex) {
> >  		struct rcar_du_group *rgrp;
>
> --
> Regards,
>
> Laurent Pinchart

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